Pope Benedict XVI opened the second African Synod of bishops on Monday, describing the continent as a 'spiritual lung' for a humanity that appears to be in a crisis of faith and hope, but also warning that African Catholics were threatened by 'spiritual waste' pouring in especially from the West.

Some 400 delegates are attending the synod until October 25. Its theme is: The Church in Africa at the Service of Reconciliation, Justice and Peace 'You are the salt of the earth... You are the Light of the world' (Mt 5:13-14).

"When we speak of the treasures of Africa, our thoughts immediately turn to the resources its land is rich in and that, unfortunately, have become and often continue to be a reason for exploitation, conflict and corruption," said the Pope.

He expressed his fears that materialism, combined with relativist and nihilist thinking was falling over the continent.

The Pope said: "the so called, 'First' World has exported up to now and continues to export its spiritual toxic waste that contaminates the peoples of other continents, in particular those of Africa."

He pointed out that religious fundamentalism, mixed with political and economic interests could hit Africa unless the church took steps to counter it.

The Pope said: "Groups who follow various religious creeds are spreading throughout the continent of Africa 'in God?s name,' teaching and practicing not love and respect for freedom, but intolerance and violence."

He was however hopeful that with its work of evangelization and human promotion, the Church can give Africa which experiences poverty, injustice, violence and wars, a great contribution.